Tuning the Coordination Environment of Single-Atom Iron Catalysts Towards Effective Nitrogen Reduction

Electrocatalytic nitrogen reduction reaction (eNRR) relies on developing efficient catalysts towards high reaction activity and selectivity. In recent years, designing single-atom catalysts have been the research frontier in electrochemical reactions. However, compared to their widely studied applications in oxygen electrocatalysis, their potential structure-function relationship and reaction mechanism in eNRR were less explored. Herein, single-atom Fe-N-x-C materials were systematically analysed considering the coordination environments of single-atom Fe. It was found that coordination environment plays a key role in determining the N-2 adsorption and activation. Among the concept catalysts designed, FeCN2 and FeCN3 offer the highest eNRR activities with a suppressed side reaction (i. e., the hydrogen evolution). Moreover, the Bader charge of the single-atom Fe and *NH adsorption energy can be the good descriptors to guide the design of eNRR catalysts. This study unravels the key role of coordination environment in tuning the reactivity of eNRR over single-atom Fe-N-x-C materials.